Not Applicable
Not Applicable
Not Applicable
The present invention generally relates to a portable lifting jack, and more particularly, a pantograph or scissors-type lifting jack for motor vehicles.
A portable jack is often stored in a motor vehicle to enable a driver to lift the vehicle to effect emergency repairs such as, for example, changing a tire. One type of portable jack for automobiles is a pantograph scissors jack. Pantograph jacks typically have four arms hinged at four joints to form a parallelogram or pantograph. One joint is formed on a base which rests on the ground while another is positioned at a load rest located vertically above the base. The other two joints are free floating and are located on a horizontal diagonal at opposite sides of the parallelogram formed by the arms. When the free floating joints are drawn together, the arms extend vertically to lift the load support relative to the base. The position of the free floating joints, and thus the load support, is controlled by a drive screw or threaded shaft which links them together.
There is continuing emphasis by automobile manufacturing companies to reduce the size and weight of components. In turn, jack manufacturing companies are continuously attempting to reduce the size and weight of jacks while still providing adequate strength to bear required loads. Accordingly, there is a continuing need for an improved jack for use with motor vehicles.
The present invention provides a pantograph jack which overcomes at least some of the above-noted problems of the related art. According to the present invention, a pantograph jack comprises, in combination, a base, a load rest, first and second lower arms each pivotably coupled at a first end thereof to the base, and first and second upper arms each pivotably coupled at a first end thereof to the load rest. Second ends of the first lower arm and the first upper arm are pivotably coupled at a first joint. Second ends of the second lower arm and the second upper arm are pivotably coupled at a second joint. The first and second joints are disposed on a substantially horizontal diagonal of a parallelogram formed by the first and second lower arms and the first and second upper arms. A drive screw extends between the first and second joints and operably moves the first and second joints toward and away from each other upon rotation of the drive screw about a longitudinal axis of the drive screw coaxial with the diagonal. A bearing support forms a bearing engagement surface along the central axis and is outwardly spaced from the second lower arm and the second upper arm. The bearing engagement surface has a lateral width greater than a lateral width of at least one of the second lower arm and the second upper arm. The drive screw has an abutment facing the bearing engagement surface. A bearing has an opening coaxial with the drive screw and receiving the drive screw therethrough. The bearing is located between the bearing engagement surface and the abutment.
According to another aspect of the present invention, a pantograph jack includes, in combination, a base; a load rest, first and second lower arms each pivotably coupled at a first end thereof to the base, and first and second upper arms each pivotably coupled at a first end thereof to the load rest. Second ends of the first lower arm and the first upper arm are pivotably coupled at a first joint. Second ends of the second lower arm and the second upper arm are pivotably coupled at a second joint. The first and second joints are disposed on a substantially horizontal diagonal of a parallelogram formed by the first and second lower arms and the first and second upper arms. A drive screw extends between the first and second joints and operably moves the first and second joints toward and away from each other upon rotation of the drive screw about a longitudinal axis of the drive screw coaxial with the diagonal. A bearing support forms a bearing engagement surface along the central axis. The drive screw has an abutment facing the bearing engagement surface. A bearing has an opening coaxial with the drive screw and receiving the drive screw therethrough. The bearing is outwardly spaced from the second lower arm and the second upper arm. The bearing has a lateral width greater than a lateral width of at least one of the second lower arm and the second upper arm. The bearing is located between the bearing engagement surface and the abutment.
According to yet another aspect of the present invention, a pantograph jack includes, in combination, a base, a load rest, first and second lower arms each pivotably coupled at a first end thereof to the base, and first and second upper arms each pivotably coupled at a first end thereof to the load rest. Second ends of the first lower arm and the first upper arm are pivotably coupled at a first joint. Second ends of the second lower arm and the second upper arm are pivotably coupled at a second joint. The first and second joints are disposed on a substantially horizontal diagonal of a parallelogram formed by the first and second lower arms and the first and second upper arms. A drive screw extends between the first and second joints and operably moves the first and second joints toward and away from each other upon rotation of the drive screw about a longitudinal axis of the drive screw coaxial with the diagonal. A bearing support forms a bearing engagement surface along the central axis. The drive screw has an abutment facing the bearing engagement surface. A bearing having an opening coaxial with the drive screw and receiving the drive screw therethrough. The second lower arm and the second upper arm each form a longitudinally extending channel. The bearing is located outside the channel of the second lower arm and the channel of the second upper arm. The bearing has a lateral width greater than a lateral width of the channel of the second lower arm and a lateral width of the channel of the second upper arm. The bearing is located between the bearing engagement surface and the abutment.
From the foregoing disclosure and the following more detailed description of various preferred embodiments it will be apparent to those skilled in the art that the present invention provides a significant advance in the technology of jacks. Particularly significant in this regard is the potential the invention affords for providing a high load bearing, high quality, light weight, relatively small, low cost assembly. Additional features and advantages of various preferred embodiments will be better understood in view of the detailed description provided below.